Circuit interrupter tripping means



Oct. 26, 1954 A. RJWOOLFOLK 2,692,928

CIRCUIT INTERRUPTER TRIPPING MEANS Filed Dec. 1, 1951 2 Sheets-Sheet 1 y/lllllll I 5 i INVENTOR.

Oct. 26, 1954 WQQLFOLK 2,692,928

CIRCUIT INTERRUPTER TRIPPING MEANS Filed Dec. 1, 1951 1 2 Sheets-Sheet 2 WW Q Patented Oct. 26, 1954 CIRCUIT INTERRUPTER TRIPPING MEANS Arthur R. Woolfolk, Wauwatosa, Wis., assignor to McGraw Electric Company, Milwaukee, Wis., a corporation of Delaware Application December 1, 1951, Serial No.'259,3'51

7 Claims.

This invention relates to a circuit interrupter and is particularly directed to the tripping means.

This invention is an improvement over that disclosed in the copending application of William D.'Kyle, Jr., and Anthony Van Ryan for Circuit Interrupters, S. N. 180,580, filed October 21, 1950, and assigned to the same assignee as the present application.

Objects of this invention are to provide a circuit interrupter which is so constructed that it will open the circuit after an overload only when there is no current flowing and which is particularly designed to be used with a reclosing circuit interrupter.

In greater detail further objects are to provide a circuit interrupter which may be a single shot, counting circuit interrupter, so arranged that it will open the circuit after a predetermined number of circuit operations.

In circuit interrupters as heretofore constructed, it has been found that in the hydraulic type of tripping means that there is frequently inadvertent pumping taking place due to minute vibrations of the pumping plunger which becomes particularly pronounced when overload current is approached. These conditions cause undesirable operation of the circuit interrupter whether it be of the overload type or sectionalizer type.

A primary object of this invention is to provide tripping means of the hydraulic type in which there is no inadvertent pumping and consequently in which there is no undesirable creeping of the counting plunger, but instead in which the circuit interrupter operates only when the current arrives at the predetermined overload value.

In greater detail further objects are to provide tripping means of the hydraulic type in which'the magnetic plunger is allowed a certain degree of motion independently of the pumping plunger and which is so constructed that when this degree of motion is exceeded by the magnetic plunger, the pumping plunger is then operated for its full and complete stroke.

An embodiment of the invention is shown in the accompanying drawings in which:

Figure 1 is a side elevation of a circuit interrupter with parts broken away and with the tripping means shown in section.

Figure 2 is a sectional view through the major portion of the tripping means with such means removed from the rest of the circuit interrupter.

Figures 3, 4, and are sectional views on the lines'3-3, 4-4 and 5-5, respectively, of Figure 2;

Referring to the drawings, it will be seen'that the circuit interrupter is mounted in a tank I which contains oil, and is provided with the tripping means indicated generally by the reference character 2 and with contact'means not shown. The tank is provided with a removable cover 3 which has insulating bushings 4 for the termi nals. The terminals, not shown, are connected through the switch means and in series with the operating coil 5 of the circuit interrupter. Referring to Figure 2, it will be seen that the tripping means comprises the coil or solenoid 5 hereinabove noted which surrounds the lower end of a cylindrical member 6 preferably formed of insulating material. Within this cylindrical member a. fixed lower endor magnetic pole l is positioned and is secured to the encircling field structure 8 whose upper portion 8' is apertured to receive the tubular, non-magnetic member 5 as shown in Figure 2.

Within the tubular member 6 a magnetic plunger 9 is positioned and is urged upwardly by means of a relatively heavy spring ill. The magnetic plunger normally rests against a shouldered portion i! of the tubular member A non-magnetic pumping plunger 12 is positioned in the reduced upper portion [3 of the cylin drical member 6 and carries a rigidly attached headed rod M on which the magnetic plunger 9 is freely slidable.

The magnetic plunger 9, it will be noted, is provided with a plurality of grooves l5, see particularly Figure 5 so as to allow free passage of oil around the magnetic plunger. The magnetic plunger 9 is recessed and receives a spring iii which is relatively lighter than the spring iiland which urges the non-magnetic pumping plunger I2 upwardly away from the magnetic plunger 9. The pumping plunger l2 normally rests against a transverse pin ll. From the construction thus far given it is apparent that the magnetic plunger 9 is allowed a limited degree of motion independently of the pumping plunger $2. The magnetic plunger moves downwardly against the action of the spring [0 until it strikes the head of the pin [4 which is rigid with the pumping plunger :2. At this time, the magnetic plunger will draw the pumping plunger downwardly. It is to be noted that a check valve I 8 is provided in the pole piece 1 and allows only upward passage of oil through the passageway l9. Also it is to be noted thatthe pumping plunger 5 2 is provided with a check valve 29 which allows only upward passage of oil through such pumping plunger. A counting plunger 20- preferably of non-magnettle-material is positioned above the "pumping;

plunger i2 and normally rests upon the stop H as shown in the drawings.

It is preferable to provide a transverse aperture 2i, see Figures 2, 3, and 4, in the pumping plunger 52 which communicates with the central aperture 22 through the pumping plunger, such central aperture being normally closed by the check valve it. Also it is preferable to provide a pair of side slots 23 in the sides of the pumping plunger [2 to allow iree passage of oil to the passageway 2i and thence to the passageway 22.

The counting plunger 20, it will be seen, will .be moved upwardly in a step-by-step manner on upward successive strokes of the pumping plunger E2. The counting plunger 20 is provided with an extension 24 which is arranged to engage an adjustable screw 25 of a tripping member 26 of the circuit interrupter so that after a predetermined number of operations of the pumping plunger the circuit interrupter will be tripped open as the circuit interrupter is biased towards open position.

In the operation or the circuit interrupter, it will be apparent that when the magnetic plunger 9 is drawn downwardly on overload that it will engage the head of the pin M and will continue moving downwardly thereby drawing the pumping plunger l2 downwardly. On cessation of current flow, the magnetic plunger and the pumping plunger will move upwardly to the position shown in Figure 2. The downward stroke of the magnetic plunger 9 is limited by the striking of the pin l4 against the upper end of the pole i. The pin it may be made of non-magnetic material if desired. It is clear also that although the magnetic plunger 9 may tremble slightly when overload current value is approached, nevertheless, no pumping will occur as the pumping plunger remains stationary during this trembling motion or the magnetic plunger. However, as soon as the magnetic plunger moves downwardly into the solenoid 5, it passes into a magnetic field of increasing strength and continues downwardly for its full stroke. During the remaining portion of the stroke of the magnetic plunger 9, the pumping plunger it moves downwardly.

It is to be understood that a slow leak is provided around the counting plunger 29, so that it will reset itself. If less than the predetermined number of operations have occurred in rapid sequence the counting plunger 2t will settle down to its initial position as shown in the drawings and the device will therefore be reset for its total number of operations.

It will be seen that a novel form of tripping means for a circuit interrupter has been provided by this invention which is so constructed that there will be no creeping or the counting plunger of inadvertent pumping of the hydraulic plunger. It will be seen further that the hydraulic tripping means will function accurately after a predetermined number of operations of the pumping plunger which occur in rapid sequence and that there will be no uncertainty as to the time or point at which tripping will occur.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

l. Non-creeping trip operating means for a circuit breaker which automatically opens under no load, said trip operating means comprising a solenoid consisting of a tubular central member and a winding surrounding said tubular member, a non-magnetic pumping plunger normally located in the upper portion of said tubular member, a counting plunger located above said pumping plunger and within said tubular member, said pumping plunger being arranged to pump measured quantities of fluid between said counting plunger and said pumping plunger in a step-bystep manner on successive deenergizations or said winding following overload, a magnetic plunger located within the upper part or said tubular member below said pumping plunger, lost motion means between said magnetic plunger and said pumping plunger, a first spring means tending to separate said pumping plunger and said magnetic plunger, and a second spring means urging said magnetic plunger upward.

2. Non-creeping trip operating means for a circuit breaker which automatically opens under no load, said trip operating means comprising a solenoid consisting of a central tube and a winding surrounding said tube, a non-magnetic pumping plunger located in said tube, a magnetic plunger located within said tube, connecting means between said plungers having lost motion allowing said magnetic plunger to move a predetermined distance with respect to said pumping plunger without moving said pumping plunger, spring means between said plungers to separate said plungers, a second spring means urging said magnetic plunger in a direction opposite that in which the n "st mentioned spring means urges said magnetic plunger, and cumulative tripping means responsive to fluid pumped by said pumping plunger.

Non-creeping trip operating means for a circuit breaker which automatically opens under no load, said trip operating means comprising a solenoid consisting of a central tube having a first and a second stop and a winding surrounding said tube, a magnetic plunger within said tube normally resting against said first stop and arranged to be drawn into said winding away from said first stop upon energization of said winding, a non-magnetic pumping plunger within said tube normally resting against said second step, a first spring means between said plungers urging said pumping plunger away from said magnetic plunger, a second spring means urging said magnetic plunger towards said first stop, lost motion mechanical connecting means between said plungers arranged to allow said magnetic plunger to move a limited distance away from said pumping plunger and thereafter rigidly connecting said plungers whereby said pumping plunger will move with said magnetic plun er upon continued motion of said magnetic plunger, and tripping means actuated fluid pumped by said pumping plunger.

a. Non-creeping trip operating means for a circuit breaker which automatically opens under no load, said trip operating means comprising a solenoid consisting of a central tube having a first and a second step and a winding surrounding said tube, a magnetic plunger within said tube normally resting against said first stop and arranged to be drawn into said winding away from said first stop upon energizaticn of said winding, a non-magnetic pumping plunger within said tube normally resting against said second stop, a first spring means between said plungers urging said pumping plunger away from said magnetic plunger, a second spring means urging said magnetic plunger towards said first stop,

said second spring means being more powerful than said first spring means, lost motion mechanical connecting means between said plungers arranged to allow said magnetic plunger to move a limited distance away from said pumping plunger and thereafter rigidly connecting said plungers whereby said pumping plunger will move with said magnetic plunger upon continued motion of said magnetic plunger, and tripping means actuated by fiuid pumped by said pumping plunger.

5. Non-creeping trip operating means for a circuit breaker which automatically opens under no load, said trip operating means comprising a solenoid consisting of a central tube having a first and a second stop and a winding surrounding said tube, a magnetic plunger within said tube normally resting against said first stop and arranged to be drawn into said winding away from said first stop upon energization of said winding, a non-magnetic pumpin plunger within said tube normally resting against said second stop, a first spring means between said plungers urging said pumping plunger away from said magnetic plunger, a second spring means urging said magnetic plunger towards said first stop, said second spring means being more powerful than said first spring means, lost motion mechanical connecting means between said plungers arranged to allow said magnetic plunger to move a limited distance away from said pumping plunger and thereafter rigidly connecting said plungers whereby said pumping plunger will move with said magnetic plunger upon continued motion of said magnetic plunger, and cumulative tripping means actuated by fluid pumped by said pumping plunger.

6. Positive action, pumping means comprising.

a solenoid consisting of a central tube having a first and a second stop within said tube and a winding surrounding said tube, a magnetic plunger within said tube normally resting against said first stop and arranged to be drawn into said winding away from said first stop upon energization of said winding, a non-magnetic pumping plunger within said tube normally resting against said second stop, a first spring means between said plungers urging said pumping plunger away from said magnetic plunger, a second spring means urging said magnetic plunger towards said first stop, said second spring means being more powerful than said first spring means, and lost motion mechanical connecting means between said plungers arranged to allow said magnetic plunger to move a limited distance away from said pumping plunger and thereafter rigidly connecting said plungers whereby said pumping plunger will move with said magnetic plunger upon continued motion of said magnetic plunger.

7. Positive action, pumping means comprising a solenoid consisting of a central tube having a first and a second stop within said tube and a winding surrounding said tube, a magnetic plunger within said tube normally resting against said first stop and arranged to be drawn into said winding away from said first stop upon energization of said winding, a non-magnetic pumping plunger within said tube normally resting against said second stop, a first spring means between said plungers urging said pumping plunger away from said magnetic plunger, a second spring means urging said magnetic plunger towards said first stop, said second spring means being more powerful than said first spring means, and lost motion mechanical connecting means between said plungers arranged to allow said magnetic plunger to move a limited distance away from said pumping plunger and thereafter rigidly connecting said plungers whereby said pumping plunger will move with said magnetic plunger upon continued motion of said magnetic plunger, said lost motion mechanical connecting means consisting of a headed pin rigidly carried byv said pumping plunger and extendin through and slidably engaging said magnetic plunger, the head of said pin being located on that side of said magnetic plunger farthest removed from said pumping plunger.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,737,649 Edsall Dec. 3, 1929 1,742,837 Wallace Jan. 7, 1930 1,805,082 Edsall May 12, 1931 2,029,780 Mazer et al Feb. 4, 1936 2,515,530 Schindler July 18, 1950 

